U.S. patent application number 10/041431 was filed with the patent office on 2002-10-17 for implantable medical device with sensor.
Invention is credited to Geiger, Mark Allen, Kinghorn, Curtis D., Leckrone, Michael Eugene, Miesel, Keith Alan, Noll, Austin F. III, Stylos, Lee.
Application Number | 20020151770 10/041431 |
Document ID | / |
Family ID | 22986182 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020151770 |
Kind Code |
A1 |
Noll, Austin F. III ; et
al. |
October 17, 2002 |
Implantable medical device with sensor
Abstract
A device and method for measuring and communicating parameters
of a brain, tissue or other organs is disclosed. The invention
includes a sensor to sense the parameter of interest and then
communicate the sensed parameter to an activation system. The
activation system may cause the parameter to be displayed,
processed or cause action to be taken. The activation system may be
entirely or partially implanted or entirely external to the
patient.
Inventors: |
Noll, Austin F. III; (Santa
Barbara, CA) ; Miesel, Keith Alan; (St. Paul, MN)
; Stylos, Lee; (Stillwater, MN) ; Geiger, Mark
Allen; (Ventura, CA) ; Kinghorn, Curtis D.;
(Lino Lakes, MN) ; Leckrone, Michael Eugene;
(Mahtomedi, MN) |
Correspondence
Address: |
Curtis D. Kinghorn
Medtronic, Inc.
710 Medtronic Parkway N.E.
Minneapolis
MN
55432
US
|
Family ID: |
22986182 |
Appl. No.: |
10/041431 |
Filed: |
January 4, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60259746 |
Jan 4, 2001 |
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Current U.S.
Class: |
600/300 ;
128/903 |
Current CPC
Class: |
A61B 5/4839 20130101;
A61B 5/031 20130101; A61B 5/0031 20130101 |
Class at
Publication: |
600/300 ;
128/903 |
International
Class: |
A61B 005/00 |
Claims
1. A device for measuring and communicating parameters of a brain,
tissue or other organs of a body comprising: an implantable first
sensor 16 capable of measuring and communicating parameters of a
brain, tissue or other organs; and an activation system 15
connected to and responding to sensor 16.
2. The device of claim 1 wherein the activation system 15 includes
a user communication system 28 that communicates information from
or about sensor 16 or may communicate alarms or other information
based on the values that sensor 16 detects.
3. The device of claim 2 wherein the activation system 15 includes
an external device 14, the external device 14 including an external
coil 22, external electronics 24 and a power source 26.
4. The device of claim 2 wherein the external device 14 includes an
ambient parameter sensor 92.
5. The device of claim 2 wherein the user communication system 28
includes a transmitter 60 and a receiver 74.
6. The device of claim 5 wherein the activation system 15 includes
an external device 14 and wherein the receiver 74 is located in the
external device 14.
7. The device of claim 5 wherein the user communication system 28
includes a display system 80 that displays or otherwise
communicates the parameter information from the sensor 16
transmitted by the transmitter 60 to the receiver 74 to a user.
8. The device of claim 2 wherein the user communication system 28
includes a display system 80 that displays the parameter
information sensed by the sensor 16 to the physician or other
user.
9. The device of claim 2 wherein the user communication system 28
includes an alarm 90 that is triggered to alert the user to a
parameter sensed by the sensor 16 that is outside of a
pre-determined range.
10. The device of claim 1 wherein the activation system 15 and
sensor 16 are co-located in the body of a patient.
11. The device of claim 1 wherein the sensor 16 and at least a
portion of the activation system 15 are both implanted in a patient
but are not co-located.
12. The device of claim 1 further comprising a control device 104
capable of taking action to effect the body of a patient wherein
the activation system 15 directs the control device 104 to take
action based on the information from or about sensor 16 or
processed from information provided by sensor 16.
13. The device of claim 1 wherein the sensor 16 is chosen from the
group consisting of piezoelectric activity sensors, intracranial
pressure sensors, ecg sensors, ultrasound sensors, acoustic
sensors, infrared sensors, air flow sensors, strap-type respiration
sensors, CO.sub.2 sensors, thermistor sensors, microwave Doppler
sensors, inductance change respiratory electrodes, temperature
sensors, eeg sensors, pH sensors, emg sensors, O.sub.2, respiration
sensors, electrolyte concentration, glucose sensors, blood
pressures sensors, heart rate sensors, posture sensors and activity
sensors.
14. The device of claim 1 further comprising a probe 12.
15. The device of claim 14 wherein the probe 12 includes sensor 16,
probe electronics 18 and a probe coil 20.
16. The device of claim 15 further comprising an external device 14
and wherein the probe electronics 18 transfers power from the
external device 14 to probe 12 to power probe 12 and uplinks sensed
parameters from probe 12 to external device 14.
17. The device of claim 15 therein the probe electronics 18
includes an AC/DC conversion system 62.
18. The device of claim 17 wherein the probe coil 20 is connected
to the AC/DC conversion system 62.
19. The device of claim 17 wherein the AC/DC conversion system 62
includes a rectifier 66 and a regulator 68 wherein the rectifier 66
is connected to probe coil 20 and converts AC power received from
the probe coil 20 to DC power.
20. The device of claim 15 wherein the probe electronics 18 further
includes a temporary energy source 64 that provides the energy to
power the probe electronics 18.
21. The device of claim 20 wherein the temporary energy source 64
is chosen from the group consisting of a rechargeable battery, a
non-rechargeable battery or a power capacitor such as a "super
capacitor".
22. The device of claim 15 wherein probe electronics 18 further
includes a long-term power source 76 that provides the energy to
power the probe electronics 18.
23. The device of claim 22 wherein the long-term power source 76 is
chosen from the group consisting of a rechargeable battery, a
non-rechargeable battery or a power capacitor such as a
"super-capacitor".
24. The device of claim 15 wherein the probe 12 includes an
electronics case 42 and wherein the probe electronics 18 is stored
in the electronics case 42.
25. The device of claim 24 wherein the electronics case 42 has a
periphery 44, wherein screw threads are placed on the periphery 44
of the electronics case.
26. The device of claim 15 wherein the probe electronics 18
includes sensor electronics 58 and a transmitter 60 wherein the
sensor electronics 58 is connected to sensor 16 and provides power
to sensor 16, directs sensor 16 to take measurements and processes
the sensed measurement signal from sensor 16.
27. The device of claim 26 wherein the transmitter 60 is connected
to sensor electronics 58 and a probe coil 20 wherein the probe coil
20 acts as an antenna and wherein the transmitter 60 and probe coil
20 communicate parameter information determined by sensor 16 to an
external device 14 by telemetry.
28. The device of claim 26 further comprising a microprocessor 102
and a storage device 78 and wherein the sensor electronics 28 and
storage device 78 are connected to the microprocessor 102 whereby
parameter measurements by the sensor 16 are processed by
microprocessor 102 before being stored in storage device 78.
29. The device of claim 28 further comprising a control device 104
connected to microprocessor 102 and wherein the sensed parameter
information controls or activates the control device 104.
30. The device of claim 29 wherein the control device 104 is chosen
from the group consisting of a pump, a valve in a CSF drainage
system, a drug delivery system or an electrical stimulation
device.
31. The device of claim 15 wherein the probe electronics 18 further
includes a temporary energy source 64 and wherein the probe coil 20
is connected to an AC/DC conversion system 62 and wherein the probe
coil 20 is inductively coupled to an external coil 22 in the
external device 24 and wherein the temporary energy source 64 is
connected to AC/DC conversion system 62 whereby inductive coupling
between probe coil 20 and external coil 22 provides power to the
probe coil 20 and through AC/DC conversion system 62, charges up
the temporary energy source 64 and whereby the temporary energy
source 64 then provides the energy to power the probe electronics
18.
32. The device of claim 14 wherein the probe 12 has a proximal end
30 and a distal end 32 and a central axis 34 and wherein the sensor
16 is located at the distal end 32.
33. The device of claim 32 wherein the probe 12 includes a probe
head 36 located at the proximal end 30, the probe head 36 having an
outer edge 40.
34. The device of claim 33 wherein the probe head 36 is roughly
discoid in shape.
35. The device of claim 34 wherein the probe head 36 includes an
embedded probe coil 20 and wherein the probe coil 20 is an
inductive coil.
36. The device of claim 35 wherein the probe coil 20 is wound
around axis 34 in the plane of probe head 36.
37. The device of claim 33 wherein screw threads are placed on the
outer edge 40 of probe head 36.
38. The device of claim 33 further comprising a storage device 78
located in probe head 36.
39. The device of claim 14 wherein the sensor 16 is separated from
the probe 12.
40. The device of claim 39 further comprising a body 48 having a
proximal and a distal end, the proximal end of the body 48
connected to the probe 12, wherein the sensor 16 is located at the
distal end of the body 48.
41. The device of claim 40 wherein the body 48 is rigid.
42. The device of claim 40 wherein the body 48 is flexible.
43. The device of claim 39 wherein the sensor 16 is connected to
the probe 12 through a body bus.
44. The device of claim 14 wherein the probe 12 has a proximal end
30, a distal end 32 and a central axis 34 wherein the probe 12
includes a probe head 36 located at the proximal end 30.
45. The device of claim 44 further comprising a body 48 having a
proximal and a distal end, the proximal end of the body 48
connected to the probe head 36, wherein the sensor 16 is located at
the distal end of the body 48.
46. The device of claim 45 wherein the body 48 is rigid.
47. The device of claim 45 wherein the body 48 is flexible.
48. The device of claim 1 wherein the sensor 16 is connected to the
activation system 15 through a body bus.
49. The device of claim 1 further comprising a second sensor.
50. The device of claim 1 further comprising a microprocessor 102
and a storage device 78 wherein the sensor 16 and storage device 78
are connected to the microprocessor 102 whereby parameter
measurements by the sensor 16 are processed by microprocessor 102
before being stored in storage device 78.
51. The device of claim 50 further comprising a control device 104
connected to microprocessor 102 and wherein the sensed parameter
information controls or activates the control device 104.
52. The device of claim 51 wherein the control device is chosen
from the group consisting of a pump, a valve in a CSF drainage
system, a drug delivery system or an electrical stimulation
device.
53. A device for measuring and communicating parameters of a brain,
tissue or other organs of a body comprising: an implantable first
sensor 16 capable of measuring and communicating parameters of a
brain, tissue or other organs; an activation system 15 connected to
and responding to sensor 16, the activation system 15 including a
user communication system 28 that communicates information from or
about sensor 16 or may communicate alarms or other information
based on the values that sensor 16 detects; a probe 12 having a
proximal end and a distal end, wherein the probe 12 includes sensor
16, probe electronics 18 and a probe coil 20, wherein the probe
electronics 18 includes sensor electronics 58 and a transmitter 60
wherein the sensor electronics 58 is connected to sensor 16 and
provides power to sensor 16, directs sensor 16 to take measurements
and processes the sensed measurement signal from sensor 16, wherein
the probe 12 includes a probe head 36 located at the proximal end
30, the probe head 36 having an outer edge 40, wherein the sensor
16 is located at the distal end of the probe 12.
54. A device for measuring and communicating parameters of a brain,
tissue or other organs of a body comprising: an implantable first
sensor 16 capable of measuring and communicating parameters of a
brain, tissue or other organs; an activation system 15 connected to
and responding to sensor 16, the activation system 15 including a
user communication system 28 that communicates information from or
about sensor 16 or may communicate alarms or other information
based on the values that sensor 16 detects; a probe 12 having a
proximal end and a distal end, wherein the probe 12 includes sensor
16, probe electronics 18 and a probe coil 20, wherein the probe
electronics 18 includes sensor electronics 58 and a transmitter 60
wherein the sensor electronics 58 is connected to sensor 16 and
provides power to sensor 16, directs sensor 16 to take measurements
and processes the sensed measurement signal from sensor 16, wherein
the probe 12 includes a probe head 36 located at the proximal end
30, the probe head 36 having an outer edge 40, wherein the sensor
16 is located at the distal end of the probe 12, wherein the probe
head 36 is roughly discoid in shape and includes an embedded probe
coil 20 and wherein the probe coil 20 is an inductive coil, wherein
the probe coil 20 is wound around axis 34 in the plane of probe
head 36; and, a storage device 78 located in probe head 36.
55. A device for measuring and communicating parameters of a brain,
tissue or other organs of a body comprising: an implantable first
sensor 16 capable of measuring and communicating parameters of a
brain, tissue or other organs; an activation system 15 connected to
and responding to sensor 16, the activation system 15 including a
user communication system 28 that communicates information from or
about sensor 16 or may communicate alarms or other information
based on the values that sensor 16 detects; a probe 12 having a
proximal end and a distal end, wherein the probe 12 includes sensor
16, probe electronics 18 and a probe coil 20, wherein the probe
electronics 18 includes sensor electronics 58 and a transmitter 60
wherein the sensor electronics 58 is connected to sensor 16 and
provides power to sensor 16, directs sensor 16 to take measurements
and processes the sensed measurement signal from sensor 16, wherein
the probe 12 includes a probe head 36 located at the proximal end
30, the probe head 36 having an outer edge 40, wherein the probe
head 36 is roughly discoid in shape and includes an embedded probe
coil 20 and wherein the probe coil 20 is an inductive coil, wherein
the probe coil 20 is wound around axis 34 in the plane of probe
head 36; a storage device 78 located in probe head 36; and. a body
48 having a proximal and a distal end, the proximal end of the body
48 connected to the probe 12, wherein the sensor 16 is located at
the distal end of the body 48.
56. The device of claim 55 wherein the body 48 is rigid.
57. The device of claim 55 wherein the body 48 is flexible.
58. A method for measuring and communicating a parameter of a
brain, tissue or other organs of a body comprising the steps of:
providing a device for measuring and communicating parameters of a
brain, tissue or other organs of a body comprising: an implantable
first sensor 16 capable of measuring and communicating parameters
of a brain, tissue or other organs; and an activation system 15
connected to and responding to sensor 16, the activation system 15
having an external device capable of transmitting power to the
sensor and receiving parameter information from the sensor; cutting
through the skin; placing the sensor 16 at a desired location
within the body; closing the skin is closed so that the sensor 16
is entirely contained within the patient's skin; bringing the
external device 14 near the sensor 16 so that power is transferred
from the external device 14 to the sensor 16; uplinking information
from the sensor 16 to the external device 14.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a device for measuring and
communicating parameters of a brain, tissue or other organs.
BRIEF DESCRIPTION OF RELATED ART
[0002] It is often desirable to measure and communicate parameters
of a brain, tissue or other organs. For example, many people have a
condition called hydrocephalus. Hydrocephalus is a condition of
excessive accumulation of CSF in the ventricles or brain cavities.
Hydrocephalus can result from congenital conditions interfering
with normal CSF circulation or as the result of a problem with CSF
re-absorption. A typical adult has a total of about 120-150 cc of
(cerebrospinal fluid) CSF with about 25 cc in the ventricles in the
brain. A typical adult also produces about 500 cc/day of CSF, all
of which is reabsorbed into the blood stream on a continuous
basis.
[0003] Different conditions can cause the CSF pressure to vary,
often in an increasing and dangerous manner. Excessive accumulation
of CSF due to hydrocephalus causes increased pressure upon the
brain. Whatever the cause, over time, this increased CSF pressure
causes damage to the brain tissue. It has been found that shunting
the excess CSF to another area of the body is therapeutically
beneficial and generally allows the patient to lead a full and
active life. Both on a short and long term basis, many physicians
believe that it is desirable to measure and read the CSF fluid
pressure.
[0004] Further, many physicians believe it is desirable to monitor
both the physiologic parameters associated with various medical
conditions but also the reaction of various organs and tissue to
treatments administered or directed by the physicians.
Unfortunately, there has not been many devices or methods available
to physicians to monitor physiologic parameters, particularly on a
continuing basis. What systems that are available often require
wires or tubes running from sensors within the patient's body to
the outside world. These wires and tubes increase the likelihood of
infection and irritation. Therefore, there is a need for a system
whereby implantable sensors may communicate with the outside world
without requiring wires, tubes or the like to pass from within the
patient's body to outside the patient's body.
SUMMARY OF THE INVENTION
[0005] A device and method for measuring and communicating
parameters of a brain, tissue or other organs is disclosed. The
invention includes a sensor to sense the parameter of interest and
then communicate the sensed parameter to an activation system where
the parameter may be displayed, processed or cause action to be
taken. The activation system may include an external device. The
present invention allows chronic and stable measurement and
communication of parameters, including parameters, to be made.
[0006] In an embodiment, the device measures and communicates
parameters of a brain, tissue or other organs. The invention
includes a sensor. The sensor in one embodiment is located at the
distal end of a probe and is preferably placed in the area of the
brain, tissue or other organ where a measurement is desired. In
another embodiment, the sensor is co-located with an implanted
device in the tissue or organ of interest. In a further embodiment,
the sensor is located in or near the tissue or organ of
interest.
[0007] In one embodiment, the sensor is part of a passive system
that allows parameter measurements to be made and communicated to
an attending practitioner when the passive system receives power
from an external source. The part of the passive system that
receives power from the external source and communicates pressure
measurements is preferably located on or next to the skin of the
patient while the sensor is located near or at the area where a
measurement is desired to be made.
[0008] The passive system couples to an external device that
provides power to the passive system. This power is used to power
the sensing operation of the sensor and to upload the sensed
information from the passive system to an external device, if
desired. As a result, when coupled to the external power source,
the passive system is able to measure and uplink measured
parameters from the sensor to an external device or to power the
operation of an implanted device.
[0009] In an alternate embodiment, the sensor is part of a system
having a long-term energy source and storage system that allows
parameter measurements to be taken periodically or upon demand,
stored and then communicated to an attending practitioner as
desired. The part of the system that provides power, stores
parameter measurements and communicates the parameter measurements
is preferably located on or next to the skin of the patient or may
be embedded in the bone of the patient such as in the skull or
pelvis.
[0010] The long-term energy source may be rechargeable. This power
from the long-term energy source is used to power the sensing
operation of the sensor, store the parameter measurements and to
upload the sensed parameter information from the system to an
external device or to an implanted device.
[0011] In an alternate embodiment of the invention, the sensed
parameter is used to control a medical device such as a pump or
valve in a CSF drainage system, a drug delivery system or an
electrical stimulation device. These medical devices may be wholly
or partially implanted.
[0012] It is an object of one embodiment of the invention to
provide a system for measuring a parameter that does not require a
continuous source of power such as a battery or power
capacitor.
[0013] It is another object of one embodiment of the invention to
provide a device that communicates a sensed parameter to an
external device.
[0014] In another embodiment of the invention, it is an object of
the invention to provide a system that stores sensed parameter
measurements to be uploaded to an external device at a later
time.
[0015] In a further alternate embodiment of the invention, it is an
object of the invention to provide a system that actively responds
to a sensed parameter to take an action.
[0016] In another alternate embodiment of the invention, it is an
object of the invention to provide a sensor of parameters that
requires the tissue of interest to be exposed only once during
implantation for implantation of the sensor and is thereafter not
exposed while providing long-term monitoring of the parameter of
interest.
[0017] It is an object of the invention in another embodiment of
the invention to provide an implantable device that provides
information about a parameter of interest which does not depend on
a battery to operate and therefore does not depend on the battery
life to remain in operation.
[0018] These and other objects of the invention will be clear from
the description of the invention contained herein and more
particularly with reference to the Figures. Throughout the
description, like elements are referred to by like reference
numbers. Further, it is clear that to changes to the description
contained herein may occur to those skilled in the art and still
fall within the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a block diagram of the invention.
[0020] FIG. 2 is a block diagram of one embodiment of the
invention.
[0021] FIG. 3 is a side view of one embodiment of the
invention.
[0022] FIG. 4 is a side cross-sectional view of the embodiment of
FIG. 3.
[0023] FIG. 5 is a side cross-sectional view of the embodiment of
FIG. 3 in place in a skull.
[0024] FIG. 6 is a side cross-sectional view of an alternate
embodiment of the invention in place in a skull.
[0025] FIG. 7 is a side cross-sectional view of an alternate
embodiment of the invention in place on a skull.
[0026] FIG. 8 is a perspective view of an alternate embodiment of
the invention.
[0027] FIG. 9 is a perspective view of another alternate embodiment
of the invention.
[0028] FIG. 10 is a side cross-sectional view of another alternate
embodiment of the invention.
[0029] FIG. 11 is a schematic drawing of one embodiment of the
invention.
[0030] FIG. 12 is a schematic drawing of another embodiment of the
invention.
[0031] FIG. 13 is a schematic drawing of another embodiment of the
invention.
[0032] FIG. 14 is a chart showing the charging and transmitting
sequence of one embodiment of the invention.
[0033] FIG. 15 is a schematic drawing of another embodiment of the
invention.
[0034] FIG. 16 is a block diagram of an alternate embodiment of the
invention.
[0035] FIG. 17 is a schematic drawing of another embodiment of the
invention.
[0036] FIG. 18 is a schematic drawing of another embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0037] The device embodying the present invention is shown in FIG.
1 generally labeled 10. The device 10 includes a sensor 16 and an
activation system 15 connected to and responding to sensor 16.
Sensor 16 is implanted in the body of a patient. In one embodiment,
activation system 15 includes an external device 14 that is located
outside the body of the patient. In another embodiment, activation
system 15 and sensor 16 are co-located in the body of the patient.
In a further embodiment, activation system 15 and sensor 16 are
both implanted in a patient but are not co-located.
[0038] Activation system 15 preferably includes a user
communication system 28. User communication system 28 may be
entirely implanted within the patient of may have a portion that is
located in external device 24. In the embodiment where activation
system 15 includes an external device 14, external device 14 may
include a portion of the user communication system 28 that includes
an external coil 22, external electronics 24 and a power source
26.
[0039] User communication system 28 is in communication with sensor
16 and may communicate information from or about sensor 16 or may
communicate alarms or other information based on the values that
sensor 16 detects. Further, user communication system 28 may
communicate information that is processed from information provided
by sensor 16 such as trends in the sensed parameters from sensor
16.
[0040] In one embodiment, user communication system 28 includes a
receiver 74. User communication system 28 preferably includes a
display system 80 that displays or otherwise communicates the
parameter information received from a transmitter 60 by receiver 74
to a user. User communication system 28 may include a display
screen 82 that displays the parameter information to the physician
or other user. Alternately, user communication system 28 may pass
the parameter information from the external device 14 to an
external computer 84, the internet or through a modem by direct
connection 86 or through telemetry 88 as is well understood in the
art. Computer 84 can display the parameter information on its
display screen 82, record the information or further process the
information. If the information is passed through the internet or
through a modem, the information may be remotely used, processed or
displayed as desired.
[0041] User communication system 28 may also include an alarm 90
that is part of the external device 14 or the external computer 84
that is triggered to alert the user to a parameter that is outside
of a pre-determined range. The alarm 90 can also take the form of
an audible or visible warning such as a warning chime or a flashing
visual display panel, a physical warning such as a vibrating alarm
or other means of alerting the user or emphasizing the status as
will occur to those skilled in the art.
[0042] Activation system 15 may also direct components to take
action based on the information from or about sensor 16 or
processed from information provided by sensor 16. For example,
activation system 15 may direct a drug pump to provide a certain
amount of a drug to the patient or may direct an electrical
stimulation device to stimulate the patient.
[0043] All or part of activation system 15 may be implanted in the
patient or may be entirely located outside the patient. Where
activation system 15 includes at least a part outside the patient,
the outside part of activation system 15 is an external device
14.
[0044] Sensor 16 may be of the type that can detect any or all of
the following, as is well understood in the art. Examples of such
sensors 16 are given below. However, it is to be understood that
the descriptions below are not intended to limit the type of sensor
16 or the specific structure of sensor 16. It is clear that sensors
16 of the types listed below are well understood to those skilled
in the art and the specific types and uses of sensors 16 will be
immediately clear to those skilled in the art. It is also clear
that the form or structure of the sensor 16 is not critical to the
instant invention so long as such sensor 16 can be implanted and
used as is described herein.
1 Sensor Type Examples: Respir- (1) Piezoelectric activity sensors:
U.S. Pat. No. 4,485,813 ation issued to Anderson et al.; 4,576,179,
3,782,368, 4,169,462, 4,185,621 and 4,443,730. These typically
describe the use of piezo transducers that are sensitive to body
breathing motions as well as impacts or forces incident from
various directions. (2) U.S. Pat. No. 5,195,529, issued Mar. 23,
1993 to Lauri Malkamaki entitled "SENSOR FOR MONITORING RESPIRATION
(3) U.S. Pat. No. 6,064,910 issued May 16, 2000 entitled
"RESPIRATOR RATE/RESPIRATION DEPTH DETECTOR AND DEVICE FOR
MONITORING RESPIRATORY ACTIVITY EMPLOYING SAME" to Jonas Andersson,
Johan Lidman and Carolina Bigert Electrolyte U.S. Pat. No.
5,234,567 entitled "Gas Sensor" issued concen- Aug. 10, 1993 to
Bryan S. Hobbs and Yat S. Chan and tration U.S. Pat. No. 5,746,898
issued May 5, 1998 to Walter Preidel. O.sub.2 U.S. Pat. No.
6,267,724 entitled "Implantable Diagnostic Sensor" issued on July
31, 2001 to David W. Taylor and U.S. Pat. No. 6,201,980 entitled
"Implantable Medical Sensor System" issued on March 13, 2001 to
Christopher B. Darrow, Joe H Satcher, Jr., Stephen M. Lane, Abraham
P. Lee and Amy W. Wang. PH As is understood in the art glucose U.S.
Pat. No. 4,703,756 issued Nov. 3, 1987 entitled "Complete Glucose
Monitoring System with an Implantable, Telemetered Sensor Module"
to David A Gough, Joseph Y. Lucisano, Jon C. Armour and Brian
DMcKean; Blood As is understood in the art pressure Intra- (1) U.S.
Pat. No. 4,984,567 issued Jan. 15, 1991 entitled cranial "APPARATUS
FOR MEASURING INTRACRANIAL Pressure PRESSURE" to Naoki Kageyama,
Hiroji Kuchiwaki, Junki Ito, Nobumitsu Sakuma, Yukio Ogura; U.S.
Pat. No. 4,971,061 issued Nov. 20, 1990 entitled "APPARATUS FOR
RECORDING INTRACRANIAL PRESSURE" to Naoki Kageyama, Hiroji
Kuchiwaki, Nissincho Aichi-gun, Junki Ito, Nobumitsu Sakuma, Yukio
Ogura, Eiji Minamiyama, Heart rate (1) ECG MONITORS--require at
least two electrodes to be attached to the body, as described in
U.S. Pat. Nos. 4,630,614 and 4,269,195. (2) ULTRASOUND--Must be
attached to the chest. (3) ACOUSTIC--Must be attached to the chest,
or nostril as in U.S. Pat. Nos. 4,421,113 4,281,651. (4)
INFRARED--Which is attached to the finger. Nothing is known of the
remote (detached) passive heart rate monitors. (5) A sensor that
detects air flow through the nostril. As in U.S. Pat. No.
4,036,217. (6) A strap that is stretched across the chest to detect
the chest movements during respiration. As in U.S. Pat. Nos.
3,802,419 and 4,540,002. (7) A device attached to the mattress U.S.
Pat. No. 3,325,799. As in U.S. Pat. Nos. 4,146,885; 4,066,072;
3,631,438; and France PV No. 43858 No. 1,480,160; (8) A CO2 sensor
that is attached to the breathing system. (9) A Thermistor sensor
that is attached to the breathing system. (10) Ultrasound or
microwave Doppler radar (invasive due to radiation). As in U.S.
Pat. Nos. 3,875,929; 3,796,208. (11) Inductance change respiratory
electrodes. As in U.S. Pat. Nos. 3,911,899; 3,658,052. temper- (a)
U.S. Pat. No.: 5,596,995 issued Jan. 28, 1997 ature entitled
"BIOMEDICAL DEVICE HAVING A TEMPERATURE SENSING SYSTEM" to Marshall
L. Sherman, Thomas M. Castellano, Jose J. Moya, (b) thermocouple
activity/ U.S. Pat. No. 5,593,431 entitled "Medical service posture
employing multiple DC accelerometers for patient activity and
posture sensing and method" issued Jan. 14, 1997 to Todd J. Sheldon
and U.S. Pat. No. 5,031,618 entitled "Position-responsive neuro
stimulator" issued July 16, 1991 to Keith R. Mullett. eeg (a)
January 1973 edition of Popular Electronics magazine at pages
40-45. (b) U.S. Pat. No.: 5,215,086 issued Jun. 1, 1993 entitled
"THERAPEUTIC TREATMENT OF MIGRAINE SYMPTOMS BY STIMULATION" by
Reese S. Terry, Jr., Joachim F. Wernicke, Ross G. Baker, Jr., (c)
U.S. Pat. No. 4,744,029 issued May 10, 1988 entitled "BRAIN
ELECTRICAL ACTIVITY ANALYSIS AND MAPPING" to Gabriel Raviv, Gil
Raviv, (d) U.S. Pat. No.: 4,753,246 issued Jun. 28, 1988 entitled
"EEG SPATIAL FILTER AND METHOD" by Walter J. Freeman (e) U.S. Pat.
No. 4,974,602 issued Dec. 4, 1990 entitled "ARRANGEMENT FOR
ANALYZING LOCAL BIOELECTRIC CURRENTS IN BIOLOGICAL TISSUE
COMPLEXES" to Klaus Abraham-Fuchs Gerhard Roehrlein, Siegfried
Schneider, ecg As is understood in the art emg (a) U.S. Pat. No.:
4,753,246 issued Jun. 28, 1988 entitled "EEG SPATIAL FILTER AND
METHOD" to Walter J. Freeman
[0045] In use, sensor 16 is preferably placed in or in contact with
the tissue, organ or other part of the body where parameter
information may be sensed. For example, sensor 16 may be placed in
or in contact with the spinal column, organs of the body such as
the liver, kidneys, the heart, the bladder, tumors or growths, body
tissue, joints, cavities, sinuses or spaces between organs or
tissue or other areas as will occur to those skilled in the
art.
[0046] Sensor 16 may be part of a probe 12 that includes sensor 16,
probe electronics 18 and a probe coil 20.
[0047] In one embodiment, device 10 has a single sensor 16.
However, device 10 may also have multiple sensors 16 sensing the
same or different parameters at a single or at multiple locations.
Where sensor 16 senses parameters other than physiological, probe
may include sensors that sense non-parameters in addition to or in
any combination with the sensors to sense parameters.
[0048] In the embodiment of the invention shown in FIGS. 3 and 4,
probe 12 has a proximal end 30 and a distal end 32 and a central
axis 34. Sensor 16 is preferably located at the distal end 32.
[0049] A probe head 36 is located at the proximal end 30. In one
embodiment, probe head 36 is roughly discoid in shape and includes
an embedded probe coil 20. Probe coil 20 is an inductive coil. In
the embodiment shown in FIGS. 3 and 4, probe coil 20 is wound
around axis 34 in the plane of probe head 36. Probe head 36
includes an underside 38 and an outer edge 40.
[0050] In the embodiment of FIGS. 3 and 4, the probe electronics 18
are stored in an electronics case 42, attached to the underside 38
of probe head 36. The electronics case 42 has a periphery 44 and an
underside 46. Electronics case 42 is preferably cylindrical with a
smaller diameter around axis 34 than has probe head 36.
[0051] As shown in FIGS. 3 and 4, sensor 16 is separated from
electronics case 42. This is preferably accomplished by locating
sensor 16 at the distal end of a body 48 connected to the underside
46 of electronics case 42. Body 48 may be made of a stiff material
such as titanium or a rigid body-compatible plastic like
polyurethane. Alternately, body 48 may be made of a flexible
material such as a flexible body-compatible plastic such as
polyurethane that is inherently flexible by its composition or
designed to be flexible by its structural design. In either the
rigid or flexible case, the material of body 48 may be any metal,
plastic, ceramic or other material that is body-compatible and is
as flexible or rigid, in varying degrees, as desired as is well
understood in the art.
[0052] In the embodiment where body 48 is rigid, sensor 16 will be
located at a fixed location relative to the electronics case 42.
Where body 48 is flexible, such as in the embodiment shown in FIG.
9, sensor 16 may be placed where desired in the brain, tissue or in
other organs wherever in the body. In particular, where body 48 is
flexible, sensor 16 may be placed where the distance from sensor 16
to the electronics case 42 varies as, for example, with
movement.
[0053] In addition, where body 48 is flexible, sensor 16 may be
placed on or in areas where it would be difficult to place sensor
16 where body 48 to be rigid. For example, where body 48 is
flexible, sensor 16 may be "slid" between the dura and the skull to
a desired position between the dura and the skull. Other locations
to locate the sensor will occur to those skilled in the art.
[0054] In a further alternate embodiment, sensor 16 may be
connected to electronics case 42 through a system known as a "body
bus". The "body bus" is a telemetry system where the patient's own
body provides the interconnection between the sensor 16 and the
electronics case 42. An example of such a "body-bus" communication
system is given in U.S. Pat. Nos. 4,987,897 and 5,113,859, issued
to Hermann D. Funke on Jan. 29, 1991 and May 19, 1992, entitled
"Body Bus Medical Device Communication System" and "Acoustic Body
Bus Medical Device Communication System" respectively, the
teachings of which are incorporated herein by reference in its
entirety. Alternately, a radio frequency telemetry approach as
described in U.S. Pat. No. 5,683,432 to Goedeke may be used to link
sensor 16 to electronics case 42.
[0055] The sensor 16 is preferably calibrated at the manufacturing
site by comparing its measurements with measurements from a
standardized sensor. Calibration coefficients, which are unique to
each sensor 16, are computed and stored in the external device 14,
probe electronics 18, storage device 78 or microprocessor 102 for
the purpose of post-measurement processing to achieve an accurate
report of the parameters measured by sensor 16.
[0056] Because probe 12 will be inserted into the body, probe 12
should be hermetically sealed to prevent the intrusion of body
fluids into probe 12.
[0057] In the embodiment shown in FIGS. 3 and 4, the proximal end
30 is located either immediately outside of or incorporated into
the skull 50 of the patient or in other bony places such as the
pelvis, sternum, scapula, to name but a few places that will occur
to those skilled in the art. This is preferably accomplished by
making the probe head 36 with a larger diameter around axis 34 than
the electronics case 42 has. Then, for example, to place the probe
12 in the skull 50, a hole 52 is drilled in skull 50 having a
diameter about the same as the diameter of electronics case 42
(FIG. 5). Hole 52 should go entirely through the skull 50 and have
the same diameter as the diameter of electronics case 42. The
sensor 16 and body 48 of probe 12 is placed through the hole 52
until the electronics case 42 contacts hole 52. Electronics case 42
is then aligned with hole 52 and pushed through hole 52 until the
underside 38 of probe head 36 contacts the skull 50. Electronics
case 42 should be dimensioned so as not to extend entirely through
hole 52.
[0058] Alternately, screw threads may be placed around the
periphery 44 of electronics case 42. In this embodiment, hole 52 is
a threaded hole with threads matching the threads of electronics
case 42. Electronics case 42 is brought into contact with hole 52
as described above. However, instead of pushing electronics case 42
through hole 52, electronics case 42 is threaded into hole 52.
[0059] In a further alternate embodiment shown in FIG. 6, screw
threads are placed on the outer edge 40 of probe head 36. Hole 52
is dimensioned to have a diameter approximately the same as the
diameter of probe head 36. In this embodiment as well, hole 52 has
threads corresponding to the threads on probe head 36. To place the
probe 12, the sensor 16, body 48 and electronics case 42 of probe
12 is placed through the hole 52 until the outer edge 40 of probe
head 36 contacts hole 52. Probe head 36 is then aligned with hole
52 and threaded through hole 52 until probe head 36 has a desired
orientation, such as flush with the skull 50. In this embodiment,
electronics case 42 may or may not have the same diameter as probe
head 36.
[0060] In another embodiment shown in FIG. 7, probe head 36 is
separated from, although connected to, electronics case 42. In this
embodiment, electronics case 42 is mounted through a hole 52 bored
in, for example, the skull 50, and body 48 with sensor 16 is still
attached to electronics case 42 in all the variants described
herein. But, in this embodiment, probe head 36 with probe coil 20
is implanted underneath the patient's skin but above or in the
skull 50. Probe head 36 may be attached to the patient's skull 50
by screws, adhesives or other means that will occur to those
skilled in the art. Alternately, a separate hole from hole 52 may
be bored into the skull 50 to receive the probe head 36. Where
probe head 36 is located in the separate hole, probe head 36 may
have screw threads placed on the outer edge 40 of probe head 36 and
the separate hole is dimensioned to have a diameter approximately
the same as the diameter of probe head 36 with threads
corresponding to the threads on probe head 36. In this embodiment,
to place the probe 12, the sensor 16, body 48 and electronics case
42 of probe 12 is placed through the hole 52. Probe head 36 is then
attached to the skull 50 as described above.
[0061] In a further embodiment shown in FIGS. 8 and 9, a burr-hole
ring 54 having an opening 56 with a diameter "A" is placed in a
hole 52 in skull 50. Burr-hole ring 54 may be screwed into the bone
of the skull 50 or otherwise attached to the skull 50 in a fashion
well known for burr-hole rings. In this embodiment, probe head 36
has a diameter about equal to the diameter "A" of the opening 56 of
burr-hole ring 54. Probe head 36 is placed in the opening 56 where
it may be held in place by means such as friction, body-compatible
adhesive or other means that will occur to those skilled in the
art.
[0062] In the embodiment of FIG. 8, the body 48 is rigid so that
sensor 16 is located a fixed distance from and at a fixed
relationship to the probe head 36. In the embodiment of FIG. 9,
body 48 is flexible. In this embodiment, the sensor 16 is placed
through the opening 56 to a desired location.
[0063] In a further embodiment shown in FIG. 10, the probe head 36
may contain all or part of the probe electronics 18. In this
embodiment, there may be no need to have an electronics case 42.
Therefore, the sensor 16 may be attached directly to probe head 36
through a rigid or flexible body 48. In use, for example to place
the device in the head, a hole 52 is drilled through skull 50 and
sensor 16 placed through hole 52 to a desired location. Then, probe
head 36 may be attached to the skull 50 as described above.
[0064] In a variant of this embodiment, the probe head 36 may be
located a distance from the hole 52. For example, the probe head 36
may be located under the skin near the clavicle or in the abdomen
at sites common for placing RF powered implantable neurological
stimulators. In this embodiment, it may be necessary to use a
burr-hole ring 54 to position the body 48 at the skull 50 so that
sensor 16 will not move with respect to the hole 52. Further, the
probe electronics may also be located in total or in part in the
body 48 in any of the embodiments described herein.
[0065] Probe electronics 18 includes sensor electronics 58 and a
transmitter 60. Sensor electronics 58 is connected to sensor 16 and
provides power to sensor 16, directs sensor 16 to take
measurements, processes the sensed measurement signal from sensor
16 and converts the sensed signal to a digital signal. This digital
signal is preferably passed to transmitter 60.
[0066] Transmitter 60 is connected to sensor electronics 58 and
probe coil 20. Probe coil 20 acts as an antenna as will be
explained hereafter. Transmitter 60 and probe coil 20 communicate
parameter information determined by sensor 16 to the external
device 14 by telemetry. Examples of telemetry systems are shown in
U.S. Pat. No. 5,683,432 entitled "Adaptive, Performance-Optimizing
Communication System for Communicating with an Implanted Medical
Device", issued on Nov. 4, 1997 to Steven D. Goedeke, Gregory J.
Haubrich, John G. Keimel and David L. Thompson, U.S. Pat. No.
5,752,976 entitled "World Wide Patient Location and Data Telemetry
System for Implantable Medical Devices", issued on May 19, 1998 to
Edwin G. Duffin, David L. Thompson, Steven D. Goedeke and Gregory
J. Haubrich, U.S. Pat. No. 5,843,139 entitled "Adaptive,
Performance-Optimizing Communication System for Communicating with
an Implanted Medical Device", issued on Dec. 1, 1998 to Steven D.
Goedeke, Gregory J. Haubrich, John L. Keimel and David. L. Thomson
and U.S. Pat. No. 5,904,708 entitled "System and Method for
Deriving Relative Physiologic Signals", issued on May 18, 1999 to
Steven D. Goedeke, the teachings of which are incorporated herein
in their entireties by reference. Other alternate means of
communication between the probe 12 and the external device 14
include amplitude shift keying (ASK), binary phase shift key (BPSK)
or quadrature phase shift key (QPSK) to name but a few choices.
[0067] In addition, in this embodiment, probe electronics 18
includes an AC/DC conversion system 62 (FIG. 11). Probe coil 20 is
connected to AC/DC conversion system 62. Probe electronics 18
allows power to be transferred from the external device 14 to probe
12 to power probe 12 and at the same time allows probe 12 to uplink
sensed parameters from probe 12 to external device 14. This
simultaneous power transfer and uplink of information is preferably
done by a technique known as absorption modulation as is well
understood in the art.
[0068] In this embodiment, AC/DC conversion system 62 includes a
rectifier 66 and a regulator 68. Probe coil 20 will be inductively
coupled to an external coil 22 in the external device 14 as will be
explained hereafter. This inductive coupling between probe coil 20
and external coil 22 provides power to the probe coil 20. This
power will be in the form of an alternating current. In this
embodiment, this AC current has a frequency of about 175 kHz
although other frequencies may be used as desired.
[0069] Rectifier 66 is connected to probe coil 20 and converts the
AC power received from the probe coil 20 to DC power. Rectifier 66
is preferably a full-wave rectifier as is well understood in the
art but may be other rectification systems as is also well
understood in the art. The DC power is passed through the regulator
68 that ensures a relatively constant DC level despite variations
in power received from the probe coil 20 due, for example, to the
relative movement of the probe coil 20 to the external coil 22. In
this way, regulated DC power is provided to power the probe
electronics 18.
[0070] In an alternate embodiment (FIG. 12), probe electronics 18
includes the AC/DC conversion system 62 described above and in
addition includes a temporary energy source 64. Probe coil 20 is
again connected to AC/DC conversion system 62. Probe coil 20 is
inductively coupled to external coil 22.
[0071] In this embodiment, a temporary energy source 64 is
connected to AC/DC conversion system 62. Temporary energy source 64
preferably takes the form of a rechargeable battery or a power
capacitor such as a "super capacitor", having for example a small
capacity such as 1 .mu.f, although larger or smaller capacities may
be used as desired and non-rechargeable batteries may also be
used.
[0072] Inductive coupling between probe coil 20 and external coil
22 provides power to the probe coil 20 and through AC/DC conversion
system 62, charges up the temporary energy source 64. Temporary
energy source 64 then provides the energy to power the probe
electronics 18.
[0073] Probe coil 20, in this embodiment (FIG. 11), also acts as an
antenna connected to transmitter 60 to transmit information from
sensor 16 to the external device 14. In this role, probe coil 20
acts as an antenna in addition to acting as an inductive coil for
receiving power from the external device 14 as described above. As
described above, probe coil 20 is a coil so that when probe coil 20
acts as an antenna, probe coil 20 is a coil antenna.
[0074] In this embodiment, probe coil 20 performs both the function
of inductively coupling with external coil 22 to receive power from
external device 14 and transmitting information from transmitter 60
to external device 14. In an alternate embodiment shown in FIG. 13,
these two functions are separated. In this alternate embodiment,
probe coil 20 performs only the function of inductively coupling
with external coil 22 to receive power from external device. But, a
probe antenna 70 is provided that serves the function of
transmitting parameter information from the transmitter 60 to the
external device 14.
[0075] In the embodiment of FIG. 12, as shown in FIG. 14, when
probe coil 20 is inductively coupled to external coil 22, probe
coil 20 receives a downburst of energy 72 from the external device
14 through the external coil 22. The downburst of energy 72
preferably lasts for a specified time period to allow the temporary
energy source 64 to be charged, for example, about 5 seconds,
although more or less time may be used as desired. This downburst
of energy 72 is converted to a regulated DC voltage by rectifier 66
and regulator 68 and charges the temporary energy source 64 to
provide temporary energy to the probe electronics 18 as described
above.
[0076] When the probe coil 20 is inductively coupled to the
external coil 22 and the probe 12 is receiving power from the
external device 14 or after the temporary energy source 64 is
charged, sensor electronics 58 directs sensor 16 to sense the
parameter and communicate the sensed parameter to the sensor
electronics 58. Sensor electronics 58 processes the sensed
parameter information and passes it to the transmitter 60 where the
parameter information is converted into a form capable of being
sent via telemetry from the transmitter 60 to the external device
14. The parameter information is then sent from the transmitter 60
and either the probe coil 20 acting as an antenna or the probe
antenna 70, to the external device 14. External device 14 receives
the transmitted parameter information through the external coil 22
acting as an antenna or the external device antenna 94, and a
receiver 74, preferably located within external device 14.
[0077] This process of sensing parameters and transmitting it to
the external device 14 may be continued for as long as the probe 12
receives power from the external device 14 or as long as the
temporary energy source 64 has power or for a lesser time if
desired. If sufficiently many occurrences of sensing parameters and
communicating the sensed parameters are desired so that the power
capacity of the temporary energy source 64 is or will be exceeded,
power may again be downloaded from the external device 14 as
described above. As a result, the temporary energy source 64 will
be recharged and the sensing and transmitting process continued as
described above.
[0078] The embodiment of probe 12 is a passive system without a
long-term power source on the probe 12. As a result, probe 12 is a
relatively low-cost device for measuring and communicating
parameters. This embodiment allows a "real time" snapshot of the
parameter of interest.
[0079] Alternately, as shown in FIG. 15, a long-term power source
76 may be provided to power the probe electronics 18. Long-term
power source 76 may take the form of a battery that may or may not
be rechargeable or a power capacitor such as a "super-capacitor" as
is well understood in the art. Long-term power source 76 must have
a capacity sufficient to power the probe 12 for a relatively long
time. Where the long-term power source 76 is used, the temporary
energy source 64 is replaced with the long-term power source 76.
Where a storage device 78 is present, as will be explained
hereafter, long-term power source 76 may also provide power to
storage device 78 as well.
[0080] In this embodiment (FIG. 11), external device 14 includes an
external coil 22, external electronics 24, a power source 26, and a
user communication system 28. Power source 26 provides power to
operate the external electronics 24 and user communication system
28 and provides power to external coil 22 that will be passed to
probe 12 through inductive coupling with probe coil 20. Power
source 26 may be either a battery or ordinary line current that has
been adapted to provide power by such means as rectifying and
filtering line AC power to produce a DC voltage as is well
understood in the art.
[0081] External electronics 24 preferably contains a receiver 74
although the receiver 74 may be a separate component connected to
the external device 14. Receiver 74 receives and processes the
parameter information transmitted by transmitter 60 and received by
external coil 22 acting as an antenna.
[0082] External device 14 may also include an ambient parameter
sensor 92. Ambient parameter sensor 92 measures ambient parameters
such as pressure, temperature and humidity. Where ambient parameter
sensor 92 is a barometer, barometer 92 measures the atmospheric
pressure. This measured atmospheric pressure is then subtracted
from the pressure measured by sensor 16 and transmitted from probe
12 to external device 14 to produce the "gauge" pressure. This
"gauge" pressure is independent of the ambient atmospheric
pressure, which is influenced by weather systems and altitude. Of
course, where ambient parameter sensor 92 measures temperature or
humidity, ambient parameter sensor 92 will be a thermometer or a
hygrometer as is well understood in the art. Further ambient
parameters will occur to those skilled in the art and are intended
to be included in the scope of the ambient parameter sensor 92.
This ambient parameter information may be displayed directly, used
to calibrate the sensor 16 or processed with parameter information
from sensor 16.
[0083] In one embodiment, external coil 22 serves both to couple
with the probe coil 20 to provide power to the probe 12 and as an
antenna to receive information transmitted by probe 12 from
transmitter 60. As such, external coil 22 is connected to receiver
74.
[0084] Alternately, an external device antenna 94 may be present,
separate from external coil 22. In this embodiment, external device
antenna 94 is connected to receiver 74 and communicates with probe
antenna 70 or probe coil 20 to receive information transmitted from
transmitter 60. In this embodiment, external coil 22 is not
connected to receiver 74.
[0085] To use the device 10 to measure a parameter of the body, the
first step is cut through the skin and place the sensor 16. For
example, if the device 10 is to be mounted on a skull 50 and the
sensor 16 placed inside a head, after the skin is opened and the
skull exposed, a hole 52 is preferable drilled in the skull 50 to
allow the sensor 16 to be placed in the head. The probe 12 is then
implanted as described above. Thereafter, the patient's skin is
closed so that the probe 12 is entirely contained within the
patient's skin.
[0086] The external device 14 is brought near the probe 12 so that
the probe coil 20 is inductively coupled to the external coil 22
and power is transferred from the external device 14 to the probe
12.
[0087] The hole 52 is then sealed with the probe 12 in place.
Thereafter, the patient's skin is re-connected over the probe 12
where the wound will heal. This will seal the probe 12 underneath
the patient's skin.
[0088] When a measurement of a parameter is desired, the external
device 14 is placed with its external coil 22 over the probe coil
20. The probe 12 is powered by transmitting a downburst of energy
72 from the external device 14. In this embodiment, the initial
downburst of energy 72 after power-up lasts about 5 seconds. This
allows the probe electronics 18 to stabilize and set up such things
as internal clocks, etc. Subsequent downbursts of energy 72 are
preferably about 2 ms long.
[0089] In one embodiment, the probe 12 does not have an on-site
battery. Therefore, on power-up the probe electronics 18 performs
an autocalibration operation to ensure that the parameter
measurements by sensor 16 will fall within the range of the probe
electronics 18. Whenever the falling edge of the downburst of
energy 72 is detected, the probe 12 uplinks its sensed parameter
measurements to the external device 14. The uplink continues for as
long as the external device 14 sends downbursts of energy 72 to the
probe 12. The frequency of uplink is controlled by the external
device 14 and cannot exceed the rate of downburst of energy 72. It
is also possible to periodically uplink the stored calibration
coefficients to the external device 14 or to uplink the stored
calibration coefficients to the external device 14 with every
uplink of sensed parameters.
[0090] In one embodiment, each uplink of the sensed parameter
measurements is transmitted from probe 12 to external device 14
multiple times, for example thrice, to compensate for telemetry or
processing errors. In a continuous mode, when the external device
14 intermittently sends downbursts of energy 72 to provide
essentially continuous power to probe 12 and receives uplinked
parameter measurements.
[0091] In addition, as explained above, calibration coefficients
for sensor 16 may be stored in the probe 12 in the probe
electronics 18, storage device 78 or microprocessor 102. Where
these calibration coefficients are stored in probe 12, these
coefficients may be uplinked from the probe 12 to the external
device for the purpose of post-measurement processing to achieve to
achieve an accurate report of the parameters measured by sensor 16.
These coefficients may be uplinked to external device 14 when probe
12 is first powered up or may be uplinked with every uplink of
sensed parameters.
[0092] Further, data such as the serial number or model number of
the probe 12 may be stored in probe 12 in the probe electronics 18,
storage device 78 or microprocessor 102 or in the external device
14. Where such serial number or model number is stored in probe 12,
this information may be uplinked to external device 14 when probe
12 is first powered up or may be uplinked with every uplink of
sensed parameters.
[0093] In one embodiment, external device 14 is a single unit that
includes the components of an external coil 22, external
electronics 24, a power source 26, user communication system 28 and
an external device antenna 94, if present. However, external device
14 may be two or more separate devices. For example, as shown in
FIG. 16, one device 96 may provide power to the probe 12 through
inductive coupling between the probe coil 20 and external coil 22,
a second device 98 may receive the parameter information
transmitted by transmitter 60 and a third device 100 may display
the parameter information received by the second device 98.
[0094] In one embodiment where probe 12 includes a passive system
24, it is critical that probe coil 20 and external coil 22 be
coupled to allow power to be passed from the external device 14 to
the probe 12 and for parameter information to be passed from probe
12 to external device 14. It may be desirable to have an audible
confirmation that probe coil 20 and external coil 22 are coupled.
This may be accomplished by probe 12 uploading a signal to external
device 14 indicating that probe coil 20 and external coil 22 are
inductively coupled. This signal may be used by the external device
14 to trigger an audible signal indicating that the probe 12 and
the external device 14 are inductively coupled.
[0095] Alternately, the loading of the external coil 22 caused by
the inductive coupling with the probe coil 20 can be detected by
the external device 14 and used to determine coupling efficiency.
This loading can be detected by monitoring the power passed through
the external coil 22. As the inductive coupling between the
external coil and probe coil 20 increases, the power passing
through the external coil 22 to the probe coil 20 will increase. By
monitoring this power and comparing instantaneous power measures,
trends in power transmission (i.e., increasing or decreasing) or a
relative maximum power transmission amount may be determined. This
information can be used to determine whether increasingly efficient
coupling positions between external coil 22 and probe coil 20 are
being reached or that the optimum coupling position has been
reached.
[0096] Further, it may be desirable to store sensed parameter
information from the sensor 16 to be transmitted from transmitter
60 at a later time. This may be accomplished by having a storage
device 78 attached to sensor 16 and transmitter 60 (FIG. 17).
Storage device 78 may be of the type disclosed in U.S. Pat. No.
5,817,137 entitled "Compressed Patient Narrative Storage In and
Full Text Reconstruction from Implantable Medical Devices", issued
on Oct. 6, 1998 to William F. Kaemmerer or U.S. Pat. No. 5,549,654
entitled "Interactive Interpretation of Event Markers in
Body-Implantable Medical Devices" issued to Richard M. Powell on
Aug. 27, 1996, both assigned to the assignee of the present
application, the teachings of which are incorporated herein by
reference in their entirety.
[0097] Storage device 78 may be located in probe head 36,
electronics case 41 or body 48 or may be located separate from but
electrically connected to the probe 12. For example, storage device
78 may be located near the clavicle in a manner similar to the
placement of the Reveal.RTM. cardiac recording device manufactured
and sold by Medtronic, Inc. of Minneapolis, Minn. Further, storage
device 78 may be directly connected to probe 12 by wires, through
the "body bus" communication system described above or other
similar communication means.
[0098] In this embodiment, probe 12 requires a long-term power
source 76 to provide power to the sensor 16, sensor electronics 58
and the storage device 78. Sensor electronics 58 would periodically
direct sensor 16 to sense the parameter of interest. Alternately,
sensor electronics 58 could be directed from a signal from the
external device 14 to direct sensor 16 to sense parameter
information.
[0099] In either case, the sensed parameter would then be
communicated to the storage device where it would be stored. Then,
either periodically or when an inquiry is made from the external
device 14, parameter information would be uploaded from the storage
device 78 through the transmitter 60 to the external device 14 as
described above.
[0100] In an alternate embodiment (FIG. 18), sensor electronics 28
and storage device 78 may be connected to a microprocessor 102 as
shown in FIG. 13. In this embodiment, parameter measurements may be
processed by microprocessor 102 before being stored in storage
device 78. Alternately, microprocessor 102 may take a series of
stored measurements from storage device 78 and process the series,
as for example, to produce a running average of the parameter
values. Such processed information may by transmitted from probe 12
to external device 14 at the time of the processing or may be
stored in storage device 78 to be transmitted to external device 14
at a later time.
[0101] The sensed parameter information may also be used to control
or activate a control device 104. In this embodiment, shown
schematically in FIG. 18, the control device 104 may control a pump
or valve in a CSF drainage system, a drug delivery system or an
electrical stimulation device, to name but a few examples. In the
embodiment shown, the control device 104 is connected to
microprocessor 102 so that microprocessor 102 controls whether the
control device 104. In use, where microprocessor 102 has determined
that a parameter sensed by sensor 16 is within a predetermined
range, microprocessor 102 activates the control device 104 to
control the corresponding medical device. When the microprocessor
102 has determined that the sensed parameter from sensor 16 is
outside the predetermined range, microprocessor 102 causes control
device 104 to either cease or diminish operation of the control
device 104.
[0102] For example, as shown in the embodiment of FIG. 18, a
drainage catheter 2 is placed in the ventricle 4 of a patient,
coupled to the control device 104. The control device 104 is
preferably connected to a peritoneal or atrial catheter 8 although
the control device 104 could be connected to a drainage bag.
Control device 104 may be a pump or a valve connected between the
drainage catheter 2 and the peritoneal or atrial catheter 8 or
drainage bag. Where the control device 104 is a pump, the pump
pumps CSF fluid from the ventricle 4 to the peritoneal or atrial
catheter 8 where it is absorbed into the body or into a drainage
bag. Where the control device 104 is a valve, the valve, when open,
allows CSF fluid to drain from the ventricle 4 through the
peritoneal or atrial catheter 8 or into the drainage bag.
[0103] In the embodiment shown, the control device 104 is connected
to microprocessor 102 so that microprocessor 102 controls whether
the pump pumps CSF fluid or the valve is open to allow the drainage
of CSF fluid.
[0104] In use, where microprocessor 102 has determined that the
parameter sensed by sensor 16 is outside the predetermined range,
microprocessor 102 activates the control device 104 to either pump
CSF fluid or to open the valve to allow the excess CSF fluid to
drain from the patient's ventricle. When the microprocessor 102 has
determined that the sensed parameter is within a predetermined
range, microprocessor 102 causes control device 104 to either cease
pumping CSF fluid or closes the valve so that CSF ceases to drain
through the valve.
[0105] The control device 104 may also control the operation of,
for example, an adjustable subcutaneously implantable fluid flow
valve in a CSF shunt system. Such a device is the Strata.RTM. Valve
Adjustable Valve manufactured and sold by Medtronic--PS Medical of
Goleta, Calif. and as disclosed in U.S. Pat. No. 5,637,083 entitled
"Implantable Adjustable Fluid Flow Control Valve", issued on Jun.
10, 1997 to William J. Bertrand and David A. Watson. Such an
adjustable valve is useful in a physiological shunt system for
controlling the flow of fluid from one part of the body to another
such as from the patient's ventricle to the patient's ventricle or
atrium. The control device 104, for example, controls the movement
of an external or percutaneously-applied magnetic field, to cause
the valve to provide a variety of pressure or flow
characteristics.
[0106] In a variant of the embodiment using the control device 104
to control a valve or pump, the control device may also control
another medical device such as a pacemaker, neurological electrical
stimulator or a drug pump.
[0107] In addition, in one embodiment, the probe electronics 18 are
located in the electronics case 42. In an alternate embodiment, the
probe electronics 18 may be located in the body 48 or in the probe
head 36.
[0108] One advantage of the device 10 described herein is that
long-term monitoring of a parameter can be conveniently performed
without risk of infection since the organ or tissue of interest,
for example, the brain, is exposed only once during implantation.
Thereafter, the probe 12 is encased within the skin of the patient
where it can measure and communicate the parameter of interest.
[0109] An advantage of one embodiment of the present invention, is
that the device does not have an on-site battery. Therefore, the
probe 12 must run a start-up sequence each time power is
transferred to the probe 12. In the present invention, this
start-up sequence involves running an auto-calibration algorithm.
This auto-calibration algorithm ensures that the pressure
measurements received from the sensor 16 will always be within the
desired range of the probe electronics 18.
[0110] It is also clear from the description above that the
invention includes a method for measuring and communicating a
parameter of a brain, tissue or other organs of a body. Without
further limiting such methods described above, the method, in one
embodiment, comprising the steps of:
[0111] providing:
[0112] an implantable first sensor 16 capable of measuring and
communicating parameters of a brain, tissue or other organs;
and
[0113] an activation system 15 connected to and responding to
sensor 16, the activation system 15 having an external device
capable of transmitting power to the sensor and receiving parameter
information from the sensor;
[0114] cutting through the skin;
[0115] placing the sensor 16 at a desired location within the
body;
[0116] closing the skin is closed so that the sensor 16 is entirely
contained within the patient's skin;
[0117] bringing the external device 14 near the sensor 16 so that
power is transferred from the external device 14 to the sensor 16;
and
[0118] uplinking information from the sensor 16 to the external
device 14.
[0119] The description contained herein is intended to be
illustrative of the invention and not an exhaustive description.
Many variations, combinations and alternatives to the disclosed
embodiments will occur to one of ordinary skill in this art.
Further, where specific values have been given, these values are
intended to be illustrative of the invention and are not intended
to be limiting. Further, specific anatomical locations for
implanting the device have been described. These are intended to be
exemplary and not limiting. The locations where the described
device can be located will readily occur to those skilled in the
art. All these alternatives, combinations and variations are
intended to be included within the scope of the attached claims.
Those familiar with the art may recognize other equivalents to the
specific embodiments described herein which equivalents are also
intended to be encompassed by the claims attached hereto.
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